I have all of my running data on Garmin that shows pre and post COVID (at least 3 bouts). I'm now 90 seconds/km slower, doing the same volume and all other thi

I have all of my running data on Garmin that shows pre and post COVID (at least 3 bouts). I'm now 90 seconds/km slower, doing the same volume and all other things being equal (except age). My diet hasn't changed, I walk the same distances, climb the same number of stairs, steps per day, weight is the same, etc. I just cannot get going. Laboured breathing, occasional randomly high heart rate at what would previously have been a LSR (long slow run) pace, where I'd been firmly in zone 3, now randomly hitting zone 5 for bit.