There is no hard and fast rule for the maximum number of tags you can have in Google Tag Manager (GTM). The number of tags you can have depends on various factors, such as the complexity of your website, the number of tracking and analytics tools you use, and the type of tags you are using.
However, having too many tags in GTM can slow down the loading time of your website, which can affect the user experience and even impact your search engine rankings. Additionally, too many tags can also make it difficult to manage and troubleshoot issues in GTM.
It's generally a good idea to keep the number of tags as low as possible, while still tracking the data you need to improve your website's performance. You can achieve this by regularly reviewing your tags and removing any that are no longer necessary or redundant. It's also a good idea to use tools like Google Analytics to monitor the impact of each tag and identify any that may be causing performance issues.