As per the company's point of view, it's not good, but they have a reason behind it. Nowadays, employees join a company, take the offer letter, and based on that, they search for another company. That offer letter will be the basis for them to ask for a raise. During this period of talent war, many companies will pay higher to retain employees in the present company or in a new company.
Building Trust with Your Employer
Now, what you have to do is create trust that you will stay there if you are really willing to stay. You can do this by performing your best in the first few days, but without fail, ask for the offer letter within 1-2 weeks. At the same time, work on building trust.
Please let me know if you need further assistance.