Red Page - Phishing Warning when Using the Admin Interface

For a few days now, I've noticed that Google is giving me a warning when I access the admin interface of my OLS server.
Strangely, this warning only appears sporadically. Sometimes, the red Google warning appears when I first load the page, but more often, it shows up when I've made changes and click the Graceful Restart button.
Even then, the warning doesn't always appear, just occasionally.
Does anyone have an idea of what might be causing this and how I can resolve it?
I have a Debian 11 server with OLS 1.7.18, so everything is up to date, and I don't use cPanel or similar tools.