Hey @Julian 

If you exceed your profile limit (e.g., having 4,000 profiles while only having a limit for 1,500), Klaviyo generally allows you to continue adding profiles, but you will likely need to upgrade to a higher plan that accommodates more profiles. If you don't upgrade, Klaviyo might restrict sending to only a portion of your profiles, which can affect how many people receive your emails.

Flows can continue to trigger for any profile as long as the profile meets the conditions set for that flow, regardless of your profile limit. 

I might be wrong here, so please confirm this with klaviyo support - 

If you have already exceeded your profile limit, it won't immediately stop your email flows from sending. However, Klaviyo may restrict how many emails you can send out in total or to specific lists/segments.

if you’re over your profile limit and haven't upgraded your plan, Klaviyo may prioritize emails to profiles that are more recently active or engaged. new profiles might not be eligible to receive emails, or they might be suppressed automatically by Klaviyo. This would explain why not every new subscriber or cart abandoner receives an email, especially if those actions occur after reaching the limit. 

Please confirm the above

If upgrading is not an immediate option, you might want to prioritize your most valuable or engaged customers by segmenting your audience. Focus your email flows and campaigns on these segments to maximize the impact of your email marketing.

I hope this helps and thank you for being part of this amazing community,

Cheers

Arpit