This is a way to make a central corner st when you’ve got an even number of Sts and eliminates the large gap formed between the corner Sts.
The stitch is worked over 2 Sts; in order I’m calling them st1 and st2.
Work a tr in st1, then a hdtr in st2, ch2 (for corner), then work a hdtr in st1 (so working in the st behind, and over the previous hdtr), and then a tr in st2.