I'm conflicted on this, it's kind of the worse of both worlds, they mark your data as deleted in the database and you don't have access to it anymore but they can keep using it indefinably as long as they don't fuck up and some legislation forces them to delete it. So now only they have access to your data but you don't anymore.

Anecdote: I was really happy about the data Google maps saved about me a couple of weeks ago when I got a letter from the migration agency which asked me to send in a list of my journeys abroad since 2017. The list was supposed to have: date traveling out, date coming back, country and purpose. Last year I was abroad 19 times and 126 of the 355 days, without Google maps collecting the data in the background for me I would have no chance in hell to get it right, and I guess the migration agency has access to this kind of data too so they can double check if I was telling the truth or not.

But in 2018 when Google introduced the possibility to mark my data as deleted, I clicked the button and lost the ability to see the data for 2017 and early 2018 which I really regretted now, because I needed to try to come up with dates and countries according to photos on my phone which had GPS coordinates and my DSLR which had just the dates.