I'm currently working in a product which was ramped down from 19 members to 5. All remaining 5 are new to product.
Current state is:
When i initially started with this project, I thought it would slow down, but there are spikes at times which results in working at whole weekends (Happened four times in 2 months).
Should I leave this product and try to move to other product or company where i should look for balanced work and timeline, product with active development or continue in current one with an hope it would slow down in near future?
My high level view of your situation seems like the system the product is built in isn't sustainable, which is bleeding into developer bandwidth which then means that developers have less bandwidth to deal with customer concerns.
I don't have the full picture (since I'm not directly in the weeds with you), but have you looked into fixing the issues at a systemic level? If escalations and SEVs are happening frequently to drain developer bandwidth, there should be enough data for some common themes to be extrapolated. Especially when customers are dropping because developer bandwidth goes to responding to these issues & not into feature development, then there's urgency from the business side to recitfy systemic issues (since the raw $ value of the lost customers can be quantified & we just need to sum them up).
If you've already taken attempts to identify and scope out fixes to systemic issues without any support from management, then I'd say you should to switch teams or companies.