They're incredibly vague on what constitutes a pre-existing condition.
It's pretty much the same definition that travel insurance companies might nobble you for, so basically anything you've been treated for in the last couple of years or anything you're taking medication for.
Taking statins ? Pre-existing condition
On medication for BP ? Pre-existing condition
Use a steroid inhaler ? Pre-existing condition
Being treated for diabetes ? Pre-existing condition
On blood thinners, including prescribed aspirin ? Pre-existing condition
On anti-depressants ? Pre existing condition
Autistic ? Pre-existing condition
Got dementia ? Pre-existing condition
Had a melanoma, BCC or SCC diagnosed or removed recently ? Pre-existing condition
I could go on ...
Basically, I'd guess you're probably talking about 40 to 50% of the adult population fall under the pre-existing condition label.
When hospitals enter a COVID death, there's a check box to say whether or not the deceased had one, or more pre-existing conditions. If checked, a pretty lengthy list of pre-existing conditions becomes available and, if memory serves me right, ends with "Other - Please State"