@TheWrights03
WiFi interference from household appliances, walls and other obstacles, distance between Satellite and Main Deco all cause WiFi speed degradation.
Main Deco speed is not that bad, but Deco M5 hardware can do better. I would suggest to start troubleshooting with it, because if Main Deco gets faster, so will Satellite Deco.
What do you use to run speed test?
What is the Internet speed at your new place and what it were at your previous place?
Do you run Deco mesh in its default Router mode or in Access Point mode?
As for Satellite Deco, I would recommend to bring it back to the same room as Main Deco and connect to Main Deco using Ethernet cable. Run speed test after that on mobile device conncted to Satellite Deco, If everything is OK with Satellite Deco hardware, in that setup devices connected to it should get same WiFi speeds as devices connected to Main Deco.
If they don't, perhaps there are hardware issues with Satellite Deco, worth investigation.
If they do, I wonder if you have very many WiFi networks from your neighbors or other types of WiFi interference causing issues when Satellite Deco is wirelessly connected to Main Deco. Because, in my tests I can get up to 200Mbps from Satellite Deco M5 that is in the same room as Main Deco.
-----------------
Also, one more thing: please turn off 2.4GHz in Deco Main Network and run speed test for devices that are only connected to remaining 5GHz WiFi band. Sometimes, WiFi band steering and dual-band causes WiFi performance issues.