As mentioned by George White, it appears that registration for this mark is not yet complete. However, marks actually used in trade are still protected, even if not (or not yet) registered.
Trademarks are only protected when used in trade, and are only protected against other uses in trader. That is that are only protected when used to identify or are associated with a product or service being sold (or rented) or advertised or marketed for sale or rental. Use by other not in connection with an sale or rental or advertising or marketing for sale or rental is not use in trade, and is in most cases not protected under US law. Some such uses can be infringements as dilution or tarnishment of the mark, but in recent years US courts have been limiting trademark protection due to First Amendment (free speech) concerns, and tarnishment and dilution cases have been much more limited since.
Also, it is a little hard to see how "Creating an on-line community" is a product or service. Consulting on how to do this is a service, of course.
Writing about online communities or a philosophy of software development using the term "Jamstack" without using it to identify any product or service being sold or marketed could probably not be infringement. Particularly if this is accompanied by a note that "Jamstack is a trademark of Netlify. XYZ is not affiliated with or endorsed by Netlify." (or something similar).
Also, if this has "has now become an industry standard term" it may have become a generic term and lost trademark protection.
(The above is based on US trademark law. Some parts of it will not apply in other countries, and other parts may not apply.)