If you have any questions about whether you need to do anything special for the upcoming DST Root CA X3 expiration in September 2021, please post them here. A staff member may split out some conversations into their own threads.
Update 30 September 2021, 17:34 UTC
Yesterday, the R3 signed by DST Root CA X3 intermediate expired as planned. If you experience problems related to certificate chaining you should first review your configuration and make sure your server/website/device is sending the correct chain with the updated R3 intermediate signed by ISRG Root X1. It is unlikely that you need to force renewal to resolve issues related to R3 signed by DST Root CA X3 expiring. This thread and many more on the community offer advice to review and resolve this problem.
Earlier today, the DST Root CA X3 expired as planned. Most problems related to DST Root CA X3 expiring will not be solved by force renewal. Please search the forum and this this thread for help to resolve the problems you are experiencing before opening a new thread.