Recent notes disappeared after subscription to icloud storage. notes are missing from icloud.com too

My friend tried sending some photos to my iphone using Airdrop but it failed saying there's no more space on my device, so I've subscribed for a 2tb storage plan on icloud.

Right after doing that, all the notes I had on my iphone have disappeared.

I read about this issue online and saw that a full sync needs to be finished before the notes will reappear so I've let the sync run for about two days and just now it finished but not all the notes have reappeared, the last notes that appear on my iphone are from a few months ago and they're order is different and the pinned ones are also missing, but the most important ones (from the last 2 months) are totally gone.

I've logged into my icloud.com account and the notes are missing from there as well.

I checked all the options in the icloud.com account but found no way to recover them (including in the data recovery section in icloud's account settings).

When I go in the iphone to settings -> icloud -> notes, I see 257 items and when i click it, in the same line as manage storage, it says 29mb, when i click it, it shows "you have 29.9 mb of notes data securely stored in icloud and availe to sync with devices". In the same window, I click "view iphone storage" -> and then in the list of apps, next to Notes, it says 80 mb, so i'm trying to understand why there's such a big delta between the 29mb and the 80mb because it shows app size 17.3mb and documents & data 62.6mb.

My questions are:

1. Why would such an issue even happen?
2. Do you know of any way to recover these notes?

I know that maybe notes isn't the best place to store such important information and I will refrain from doing that in the future, but the info I had there is utmost important, can you think of any way to recover these notes?

Please advise,

Thanks!

Anna