Problem with certificates, reinstall didn't help

I am using Ubuntu 20.04 and I have problems with ca-certificates. When I run command sudo apt update, I receive a lot of errors like:

Certificate verification failed: The certificate is NOT trusted. 
The certificate issuer is unknown.
Could not handshake: Error in the certificate verification

Or when I run curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh (or with -k option),

I receive

curl: (77) error setting certificate verify locations:
  CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs

I tried followings without success:

sudo apt-get install --reinstall ca-certificates

sudo ln -s /etc/ssl/certs/ca-certificates.crt /etc/pki/tls/certs/ca-bundle.crt

export CURL_CA_BUNDLE=/etc/ssl/certs/ca-certificates.crt

Interestingly, I discovered that half of the /etc/ssl/certs/ca-certificates.crt file has normal line-ending, other half has different line-endings.

First half of ca-certificates.crt:

Second half of ca-certificates.crt:

I correct the file with dos2unix but I am getting still errors.

What is the root cause of the issue and the solution?

Thanks.