I think it's safe to say that all product releases come with some sort of delay or scope change, it's to be expected. But, it can oftentimes impact the morale of the team if there are repetitive delays.
The biggest thing you can do is be transparent from the beginning. Oftentimes, if you're working closely with your product teams, you can get a sense if things may slip and dates may change. When you get that feeling, it's important to have a conversation with your PMs about it so that you can relay information to your team as soon as possible.
I have three tips...
First, turn delays into a positive. Not always possible, but when you can, it's a big help. For instance, if a launch slips a month or quarter, position it to the group as an opportunity to do that extra thing on the website that could help increase conversion or write those extra blog posts to be used in social that could drive better awareness. Again, it's not always possible, especially if you work for a larger business where teams workloads are planned out, but it can help.
Second, always come with a new plan. This goes hand in hand with the above point, but if you hear from your PMs that a launch is delayed, make sure to go to your stakeholders with new dates and timelines - echoing that they have more time to build out these deliverables.
Third, drive home the point that building software or launching new products is really, really hard. Oftentimes, development teams hit unforeseen complications that delay things - it's to be expected. From the beginning, set this tone with the team and let them know that there may be changes in scope and that it's important to be flexible, because at the end of the day whatever you're launching is going to have a great impact on your business or customers.