Away from the UK most of the tax year - can I ask to be considered a non-resident?

I spent less than 75 days in the tax year of 2019-2020 in the UK. For about 3.5 months in that tax year I was renting a flat in London (it’s that long because there was a one month notice – essentially I vacated the flat earlier). During the rest of the year I was staying in hotels whenever I was visiting the UK.

For about 7 months of that year I was working as a regular for a UK-based company and my salary was taxed as usual as a UK PAYEE. However, during most of that period I was residing in another country (Bulgaria).

I would strongly prefer that my income from that UK job is taxed in Bulgaria rather than in the UK as the tax rate is lower.

Can I build the case with the UK HMRC that I have been a non-resident?

As said, my main points are:

• I was physically present in the UK only for 73 days during the whole tax year
• For almost 9 out of 12 months I, essentially, did not have a residence of any kind in the UK
• I spent more than 9 months of that tax year in Bulgaria
• I haven’t regained any residence in the UK (I continue to reside in Bulgaria, essentially, 100% of the time)

How strong would be such a case? And what is the procedure involved?

EDIT: The answer to this post states that earnings from an UK employment is a UK source income which is taxable in the UK no matter whether there is residence in the UK or not. Can anyone comment on this?