Slow Internet Since Outbreak of COVID-19

Since COVID-19 started impacting everyone (March 2020), I have been experiencing extremely slow internet download speeds for my 150 Mbps service, as low as 5 to 10 Mbps at certain times during the day. I contacted Cox Support, who reset my modem and got the speed back up to 100 to 120 Mbps download for a moment, but within less than 5 minutes my download speed returned to 5 to 10 Mbps. I live in a large apartment building, just me in the residence using 1 device a a time.  I realize that more people are working from home, their kids are using up more bandwidth as they stay home, etc., but should the speed reduction be this extreme?  Are lots of people having this same issue?