I believe Windows 10's policy, now that it releases two versions each year (H1 and H2), is to service each version for 2 years (or is it 1.5 years?)... it's been 1 3/4 years since the introduction of 1909.
Windows is no longer supporting version 1909,including security updates. (I don't know if this includes support for Microsoft Defender AV). [URL] This caught me by surprise, as it seemed like only yesterday that MS dropped support for Win 7. Because I always defer upgrades and updates, on my test laptop my support expired without warning. I had to invoke Windows Update "Check for Update" several times to get the latest 20H2 version to install, which took many hours. Just a word to the wise.
Windows 10, version 1909 end of servicing (Home and Pro)