I've noticed that at the early stages of product development each agile dev team I've worked in used Scrum and gradually migrated to Kanban as the product matured. I don't think it was a coincidence. I actually think that by design Scrum works well during early stages, while Kanban may be a better choice for mature products.
At the very beginning of the product life cycle the dev team needs to deliver a minimum viable product as soon as possible. Scrum defines a framework for a process that should help to achieve that. When a team follows Scrum prescriptions it works in short and very focused sprints, the stakeholders have clear expectations of the outcome of each sprint, and daily standups, planning, review and retro sessions give an opportunity to developers to share information, discuss priorities and scope, assess the progress, and find opportunities for improvement.
In ideal world, if the product owner defines the right scope and sets the right priorities, every story shipped by the dev team brings the product closer to the releasable state. Also, Scrum recommends building cross-functional dev teams. Such teams are especially productive when working on the small codebase of a new product where each developer has a chance to work on every product component and there is little need for narrow specialisation.
However, as the product matures after a few big post-MVP releases the development team becomes less busy with new development. At that stage devs spend more time on support, bug fixing, minor improvements, and paying out tech debt. As a result, it becomes increasingly harder to set a single well-defined goal for a sprint. Instead, a team may have two-three smaller goals.
The idea of working in sprints may become less relevant as well. A lot of tasks at this stage have relatively low priority, unless they are major bugs, security issues or have hard deadlines, i.e. the end of financial year.
In response to those changes the dev team has to adjust their development process. The devs change sprints duration. Eventually they stop using sprints to structure their work at all. Sprint planning and review sessions get replaced by less frequent roadmap planning and weekly backlog grooming sessions. The team typically still has retros, just maybe less often. Daily standup is the only meeting that is never removed from the calendar, though.
In addition to that, the team finds it useful to limit the number of work-in-progress items on their board to make sure that every task is completed as quickly as possible and prioritises the tasks that are closer to “done” state over the “not-started” ones. This process looks more like Kanban and that makes sense as at that stage the goal for the team is typically to maintain the product and incrementally improve it, rather than ship new features as soon as possible.