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Recently 'git clone' was faling with the error: 'fatal: unable to access 'https://github.com/repo/here/': Failed sending HTTP2 data'
I fixed it by downgrading the libcurl3-gnutls package and pinning it:
sudo aptitude install libcurl3-gnutls=7.64.0-4+deb10u2
sudo apt-mark hold libcurl3-gnutls
Afterwards git clone works as expected, a bug report has already been filed upstream:
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