A German Unicorn gave me a written pre-offer before a trial day (where you have to take a day off to work for them), after the day I very quickly received the feedback that they've identified areas where I need to improve/learning, and that they would really like to hire me (verbal final offer with the pre-offer compensation).

I told them I have a few other offers on the way, e.g. from FAANG, so I wanted 1-2 weeks to think about where I'd like to go next.

Today, less than one week after the verbal offer, they amended the offer and reduced total comp. by 4k€/$, telling me I'd need another 6-12 months to get to the level for the +4k€/$.

Is this a clear red flag? I've never experienced this before.