Also, Aboelens12!
This is a reply from this thread, by another user who also had this issue, and they claim these steps fixed the issue for them:
“THIS WORKED FOR ME:
from chdjparadise1 Apr 19, 2023
Go to Settings > [your name] > iCloud, and make sure that the toggle next to Maps is turned on. If it is turned off, turn it on and wait for a few minutes to see if your favorites and guides reappear...On my settings the toggle button was set to on. So, what I did was toggled the Maps off then back on waited a minute then launched the Apple Maps app and all My Guides reappeared.…”
Good Luck!