Hello, thank you for your report.
The base armor of a starbase gets increased by the amount the tooltip suggests, so for example upgrading to a starport should increase the armor hit points by +2000 which it does, making a starport have 4000 base armor compared to a starbases 2000.
The tooltips could be clearer at explaining this and where the armor is coming from so we will make a ticket about it and see what can be done.
The base armor of a starbase gets increased by the amount the tooltip suggests, so for example upgrading to a starport should increase the armor hit points by +2000 which it does, making a starport have 4000 base armor compared to a starbases 2000.
The tooltips could be clearer at explaining this and where the armor is coming from so we will make a ticket about it and see what can be done.