Website padlocks signify the site has a secure communication between your browser and the website server. The site has SSL certification. This is a good thing. You should still be able to access these sites. You cannot remove the padlocks.
Thank you Barry. Regret I can't access any of the sites on my iPad. The same sites are on my iPhone and the padlocks don't appear there. Can open any of those sites.The padlocks only appeared two days ago!
That suggests it would be worth a look at Settings: 'Screen Time' > 'Content & Privacy Restrictions'. You may inadvertently have locked yourself out of some class of content.
It can be surprising what is marked as age-restricted sometimes. My young niece once wanted to show us some artwork she had posted to a sharing site. I was surprised to have to go through 3's adult-content permissions to be able to access it on my phone. Niece's drawings were entirely innocent but, as the site lets adults post, it's cautiously graded as 'mature').
How very odd! These things have become so complex that I probably shouldn't be surprised. I had one long-standing program that after working perfectly for 4 years and with no recent upgrade to either it or my operating system suddenly refused to save changes to my work. Neither I nor Apple nor the program author could fathom it out. In the end I deleted the program and reinstalled it from its original installer and everything has worked correctly since then.
My understanding the greyed out padlocks show that the connection to that site is secure (encrypted) and was reached by a secure https request. Unlike an unsecure (unencrypted) http request. As per this link.