This package use multiple upstream tarballs.

See
https://raphaelhertzog.com/2010/09/07/how-to-use-multiple-upstream-tarballs-in-debian-source-packages/

Example of updating from 4.16.6 to 4.17.4

Step 1: Download both tarballs
uscan --verbose

This will create node-lodash_4.17.4+dfsg.orig.tar.xz and
 lodash-methods-4.17.4.tar.gz will need to be downloaded manually.
 See commented entry in watch file for downloading this file.

Note: due to a uscan bug, excluding files from gitlab.com tarballs don't work.
So node-lodash_4.17.4+dfsg.orig.tar.xz will need to be generated manually.

Rename second tarball to
 node-lodash_4.17.4+dfsg.orig-modules.tar.gz

Step 2: Extract previous version's dsc file
dpkg-souce -x node-lodash_4.16.6+dfsg-2.dsc

Step 3: Use uupdate to use first tarball
cd node-lodash-4.16.6+dfsg
uupdate -v 4.17.4+dfsg ../node-lodash_4.17.4+dfsg.orig.tar.xz

Step 4: Extract second tarball
cd ../node-lodash-4.17.4+dfsg
tar -zxvf ../node-lodash_4.17.4+dfsg.orig-modules.tar.gz
mv lodash-4.17.4-npm-* modules

Step 5: Create dsc file
dpkg-source -b .

Step 6: Import dsc file to git
cd ../node-lodash
gbp import-dsc --pristine-tar ../node-lodash_4.17.4+dfsg-1.dsc

Step 7: Modify and build
Make changes in the git repo and generate dsc file
dpkg-source -b .
cd ..
sbuild -sA -d unstable node-lodash_4.17.4+dfsg-1.dsc