I have the same problem in Emacs 29.1. I believe it is due to the svn backend being called asynchronously, with large file annotations thereby being cut off before they are done.
The following change solves the problem for me:
--- /home/ue/tmp/vc-svn.el.orig 2023-12-20 13:36:06.427678047 +0100
+++ /home/ue/tmp/vc-svn.el 2023-12-20 13:33:43.881904459 +0100
@@ -770,7 +770,7 @@
;; Support for `svn annotate'
(defun vc-svn-annotate-command (file buf &optional rev)
- (apply #'vc-svn-command buf 'async file "annotate"
+ (apply #'vc-svn-command buf nil file "annotate"
(append (vc-switches 'svn 'annotate)
(if rev (list (concat "-r" rev))))))
--