@Quveas
''To you maybe. My employers disagree with you, and we have no shortage of highly qualified people wanting to work for us who are happy to provide full references as we require. ''
But again you are missing my point.
This is not about the candidate being ''happy to provide full reference'' or not.
It is not the candidate choice to make if their previous employer (who they might have been with for years) has a policy not to comment on performance and only provides basic facts, there is nothing the candidate can do to change that.
My point was that your blanket policy penalises the candidate for something they have no control on.
It is nothing to do with the candidate or their performance if their current employer, like many others, does not provide comments on performance from line managers.
Companies often do that now because they want to protect themselves from staff with line management responsibilities not being objective in their comments/references and to avoid legal come back by the candidate.
Any decent company/HR team would be aware of that. Your blanket policy to me is therefore nonsensical.
A basic reference can include data like sickness records because again that is recorded data that no one can challenge.
OP, most companies will request sickness records for 12 months to 2 years when taking references. Then it will depend on your current employer's policy as to whether they share this or not.
If that comes out you simply need to explain that you developed Covid and some complications but that you are now in better health. It won't be uncommon for people to have had that experience.