The Fritz!Box 7583 came onto the market in 2019 and can MESH ... the difference to the FRITZ!Repeater 1200 AX is that the old Fritz!Box 7583 cannot yet do "AX" and in this respect both "understand" each other excellently via MESH, only that the Fritz!Box 7583 is "backwards compatible" with the repeater. In this respect, I do not expect any problems ...

The repeater can handle the "modern" protocols Wi-Fi 5 / 802.11ac, Wi-Fi 6 / 802.11ax and comparatively
"only" protocols up to Wi-Fi 5 / 802.11ac
The following document describes the differences between the protocols (... from 2009, when Wi-Fi 4 was introduced ....):
https://praxistipps.chip.de/wifi-4-wif...

I have the Repeater 1200 AX in operation with the Fritubox 7590 (without AX!). From my point of view (layman), it works perfectly. In places with unreliable wifi connections, the connection is now stable and fast.