HTTP 429 because of Android app?

As my FreeBSD nextcloud instance did not survive an update (this happens from time to time), I have reinstalled

Debian 10
PHP 7.4
nginx 1.14.2

Result: everything was fine until I logged in with my phone.

Since then, I get no longer web browser access. Instead, I get HTTP 429. Same thing with the Android app…

Is your Nextcloud instance running in a hosted environment?