App Platform: Not found sub static pages

I have this NextJS static site with 3 pages (/, /sub/page1, /sub/page2).

It all works on local machine, and saw those 2 sub pages in build logs.

[2021-08-09 20:55:04] Page                              Size     First Load JS
[2021-08-09 20:55:04] ┌ ○ /                             103 kB          180 kB
[2021-08-09 20:55:04] ├   /_app                         0 B            73.5 kB
[2021-08-09 20:55:04] ├ ○ /404                          3.18 kB        76.7 kB
[2021-08-09 20:55:04] ├ ○ /sub/page1                   2.58 kB        79.9 kB
[2021-08-09 20:55:04] └ ○ /sub/page2                   2.48 kB        79.8 kB
[2021-08-09 20:55:04] + First Load JS shared by all     73.5 kB
[2021-08-09 20:55:04]   ├ chunks/framework.c93ed7.js    42.6 kB
[2021-08-09 20:55:04]   ├ chunks/main.655ad0.js         20.3 kB
[2021-08-09 20:55:04]   ├ chunks/pages/_app.00ff22.js   8.88 kB
[2021-08-09 20:55:04]   ├ chunks/webpack.415df0.js      1.72 kB
[2021-08-09 20:55:04]   └ css/a53ece9f561abae757e6.css  2.28 kB
[2021-08-09 20:55:04] 
[2021-08-09 20:55:04] λ  (Server)  server-side renders at runtime (uses getInitialProps or getServerSideProps)
[2021-08-09 20:55:04] ○  (Static)  automatically rendered as static HTML (uses no initial props)
[2021-08-09 20:55:04] ●  (SSG)     automatically generated as static HTML + JSON (uses getStaticProps)
[2021-08-09 20:55:04]    (ISR)     incremental static regeneration (uses revalidate in getStaticProps)
[2021-08-09 20:55:04] 
[2021-08-09 20:55:05] info  - Using webpack 5. Reason: Enabled by default https://nextjs.org/docs/messages/webpack5
[2021-08-09 20:55:05] info  - using build directory: /workspace/web/.next
[2021-08-09 20:55:05] info  - Copying "static build" directory
[2021-08-09 20:55:05] info  - No "exportPathMap" found in "next.config.js". Generating map from "./pages"
[2021-08-09 20:55:06] info  - Launching 7 workers
[2021-08-09 20:55:06] info  - Exporting (0/4)
[2021-08-09 20:55:06] info  - Copying "public" directory
[2021-08-09 20:55:06] info  - Exporting (1/4)
[2021-08-09 20:55:06] info  - Exporting (2/4)
[2021-08-09 20:55:06] info  - Exporting (3/4)
[2021-08-09 20:55:07] info  - Exporting (4/4)
[2021-08-09 20:55:07] Export successful. Files written to /workspace/web/out
[2021-08-09 20:55:16] 
[2021-08-09 20:55:16] => Using static site output directory out
[2021-08-09 20:55:16] => Using document root /workspace/web/out
[2021-08-09 20:55:16] => Uploading files to Spaces
[2021-08-09 20:55:16]     404.html
[2021-08-09 20:55:17]     _next/static/D_atJx2K517nLQa-IEg6T/_buildManifest.js
[2021-08-09 20:55:17]     _next/static/D_atJx2K517nLQa-IEg6T/_ssgManifest.js
[2021-08-09 20:55:17]     _next/static/chunks/10.f75ce268f49e89acdd00.js
[2021-08-09 20:55:18]     _next/static/chunks/198.f37c103fa39a0f350427.js
[2021-08-09 20:55:18]     _next/static/chunks/214.9f4b917a2fb0e82c9f73.js
[2021-08-09 20:55:19]     _next/static/chunks/2c796e83.c4bfdc924d2fb2c8c18d.js
[2021-08-09 20:55:19]     _next/static/chunks/2df5cbd4-314b274ddcc3cf723dfc.js
[2021-08-09 20:55:19]     _next/static/chunks/387.f587573ff3f7573625f6.js
[2021-08-09 20:55:20]     _next/static/chunks/570.2c6c8781eb3261e287a9.js
[2021-08-09 20:55:20]     _next/static/chunks/578.216282282ab2726ebd89.js
[2021-08-09 20:55:20]     _next/static/chunks/611-1044feb5cfc5c3d337ae.js
[2021-08-09 20:55:20]     _next/static/chunks/947-00450b08213316ffb0e8.js
[2021-08-09 20:55:20]     _next/static/chunks/framework-c93ed74a065331c4bd75.js
[2021-08-09 20:55:21]     _next/static/chunks/main-655ad0ce567efa01caa9.js
[2021-08-09 20:55:21]     _next/static/chunks/pages/_app-00ff2223b1bdf8be4954.js
[2021-08-09 20:55:21]     _next/static/chunks/pages/_error-9faf4177fb4e528b4124.js
[2021-08-09 20:55:21]     _next/static/chunks/pages/index-deeab5780fba94d69397.js
[2021-08-09 20:55:21]     _next/static/chunks/pages/sub/page1-28ca58748f288a98cb31.js
[2021-08-09 20:55:21]     _next/static/chunks/pages/sub/page2-d20eef6f22fc54eded17.js
[2021-08-09 20:55:22]     _next/static/chunks/polyfills-a54b4f32bdc1ef890ddd.js
[2021-08-09 20:55:22]     _next/static/chunks/webpack-415df06d39239d2b5694.js
[2021-08-09 20:55:22]     _next/static/css/a53ece9f561abae757e6.css
[2021-08-09 20:55:22]     favicon.ico
[2021-08-09 20:55:22]     index.html
[2021-08-09 20:55:23]     sub/page1.html
[2021-08-09 20:55:23]     sub/page2.html
[2021-08-09 20:55:23]     vercel.svg

But when I go to the live app, sub pages shows 404. Please help me.