If you are looking for these versions because your PC can't handle the newest AI-heavy Premiere Pro 2024, Adobe actually allows you to download older versions directly through the (under "Other Versions"). This gives you the stability of the 2018/2021 code without the malware risks of a random download.
While "fixed" versions promise a smooth experience, they come with a "ghost in the machine." Many files hosted on unverified forums include: Adobe Premiere Pro Cc 2018 2021 Download Highly Fixed