Visual output bug since the new 4.49.0 release with jupyter lab:

from tqdm.auto import tqdm
import tqdm as t
print(t.__version__)
import time

pbar = tqdm(
    total=None, 
    leave=False, 
    bar_format="{desc}[{n_fmt}/{total_fmt}] {percentage:3.0f}%|{bar}{postfix} [{elapsed}<{remaining}]", 
    initial=1,
    desc="Iterations"
)

for _ in range(10):
    time.sleep(0.5)
    pbar.update(1)    
    
pbar.close()

gives

When I remove bar_format visual output looks better.

• I have marked all applicable categories:
  • exception-raising bug
  • visual output bug
  • documentation request (i.e. "X is missing from the documentation." If instead I want to ask "how to use X?" I understand StackOverflow#tqdm is more appropriate)
  • new feature request
• I have visited the source website, and in particular
  read the known issues
• I have searched through the issue tracker for duplicates
• I have mentioned version numbers, operating system and
  environment, where applicable:

  import tqdm, sys
  print(tqdm.__version__, sys.version, sys.platform)

4.49.0 3.7.7 (default, Mar 23 2020, 22:36:06)
[GCC 7.3.0] linux