Fastboot EU rom is ONLY when there is no TWRP available.
As soon a solution is given EU rom is moved to zip install.
Fastboot ROMs only exist until a TWRP is available for your phone.
Check this post from @gogocar62 : https://xiaomi.eu/community/threads/21-7-21-22.62299/post-620104
Thank you both for the fast response.
Yes I noticed that in a earlier post but because that twrp-3.5.2-renoir-Nebrassy.img is listed as unofficial, I thought it wasn't safe to use yet.
So it looks like to keep my phone updated from now on, I need to explore how to install this twrp and use the phone's built-in Updater app?