Popups instead of redirects due to the first response to API request is randomly returned as "200 text/html"

[hrsa]

Hello,
There's an issue i've been struggling with in Inertia for almost a month now.
I've created a dockerized Laravel Inertia app with source code available at GitHub.
It runs on https://calendize.it/

I'm struggling with the API sporadically returning "code 200 text/html" responses, even when it's not supposed to.
This happens a lot on the login screen, where the login is basically broken.
I've created a topic at Laracasts with no feedback.
I've tried putting ray calls in the controllers - and they return correct responses (jsons or Inertia pages when requested).
I've tried disabling nginx caching.
But still - once in a while (right now, for example), the server suddenly starts responding with "code 200 text/html" , which messes up the app - the email check won't work and the login won't neither (request content with a redirect is opened in a popup).

[hrsa]

Update - the culprit was the crypto-miner malware the crept it through the exposed php container port and hogged all the CPU processing power.
Nothing to do with Inertia!